Wood stain



Patented July i938 WOOD STAIN Elwood J. Schuessele, Jenkintown, Pa., assignor to TheLawrence-Mcladden 00., Philadelphia, Pa., a corporation of Pennsylvania No Drawing.

8 Claims.

. This invention relates to stains and particularly to wood stains which are substantially free from shade changing effects.

In the production of wood stains, the water 5 soluble aniline dyes have proved to be most suitable as coloring components principally because of their substantial fastness to light. The use of these water soluble dyes in wood stains, however,

requires a suitable solvent and the solvents here- 10 tofore proposed have given rise to disadvantages inthe finished wood stains. In this connection it its important to note that the dissolving ability of the solvent is only one of a number of factors which must be considered." For instance, water is a solvent for these dyes, but it is not a suitable solvent for use in wood stains due to the fact that it raises-the grain of the wood. Furthermore,

the use of water as a solvent gives rise to unsatisfactory penetration of the dye into the wood.

It'has been proposed to use methyl alcohol as a solvent but when this is done it is necessary to convert the dye to an alcohol soluble form and the disadvantages of grain raising and lack of pene tration are only partly alleviated. Moreover,

where methyl alcohol is used as the dye solvent there is a pronounced tendency to bleeding of the color in the stain into lacquer or similar coatings subsequently applied to the stained surface.

It has also been proposed toemploy the more complex organic compositions such as the glycols and their alkyl ethers as solvents for use in wood stains. These complex organic compounds have certain serious disadvantages when used in wood stains. Perhaps the most serious of these disadvantages is that a stain made with one of these compounds as the principal solvent ingredient tends to undergo a change in shade during the period between the time that the stain is made up and the time when it is applied. The term 40 shade-changing effect as used throughout this specification and the claims is meant to refer to this effect which takes place before application and is to be distinguished from the term fading effect which is used to refer to fading 45 ofthe color which takes place after application. This shade-changing effect is quite apparent over periods as short as a week or less. It is probably derived from a number of causes,

among which are precipitation of the dye, col- 50 loidal dispersion of the dye and changes in the Application July 14, 1936, Serlal'No. 90,537

chemical structure of the dye. Whatever may be the causes, it will be readily understood that shade-changing is a-disadvantage of serious import, since it makes it practically impossible to produce a stain to match a given shade unless the 5 application is to take place within a relatively short period of time after the stain is prepared. Moreover such stain as is not used in a given application will not match the shade so obtained if additional material is to be stained at a later 10 date with the same stain. In addition, the glycols and their alkyl ethers are hygroscopic and this results in grainraising when the atmosphere is relatively humid.

An additional problem in the wood staining art 15 has to do with the production of reducer solutions which consist of all of the essential ingredients of a wood stain except the dye. Such reducer solutions are made up into stains by adding the desired dye directly to the reducer solution. Here- 20 tofore reducer solutions have not proved practical due to the fact that in order to get the dye into solution it was necessary to use relatively large amounts of solvent in the reducer as compared with the amount of solvent which would be 25 suificient where the wood stain was made up in the customary fashion, and this increased the cost of the finished stain. The difficulty, therefore, resided in the characteristics of the solvents heretofore proposed for use in reducer solutionsgo Therefore. the main object of the present invention is to overcome the disadvantages in herent in the wood stains of the prior art by the use of a dye solvent which makes it possible to produce wood stains substantially free from shade-changing effects prior to application and substantially free from fading effects after application andfwhich penetrate the stained surface without causing any substantial grain raising and at the same time'are free from bleeding 40 effects.

A further object of this invention is to produce a practical wood stain reducer solution comprising all of the essential components of a' wood stain except the color ingredient which may be added to the reducer solution when desired.

In the practice of this invention the preferred dye ingredient is selected'from the group comprising the water soluble aniline dyes. The spe. ciflc dyes set forth below are examples of dyes which are suitable for the production of the colors ordinarily used in wood stains. Wherever possible the color index number i'ollows the name of the dye.

The following reds are suitable:

'Azo rubine '179 Carmoisine 179 Croceine scarlet M00 252 Brilliant croceine scarlet conc. Fast red conc. 176 Suitable oranges are:

Acid oranges such as, Acid orange A 151 Acid orange Y 151 Acid orange II 151 Croceine orange 26 Suitable yellows are:

Naphthol yellow 10 Tartrazine .640 Metanil yellow MXX 13B Suitable blacks are;

Buifalo black NBR conc. 246 Acid black BX 267 Fast black B 996 Naphthylamine black 10 BR 246 a Suitable browns are:

Resorcin brown 234 Benzo brown B 608 Suitable greens are:

Wool green S 737 Acid green B 666 As a blue, acid blue R (Manual of Dyeing, by

, dye ingredients.

Knecht, Rawson and Loewenthal, published London, 1917, by Charles Griflin & Co., Ltd., Fourth Edition, Vol. 2, page 549) may be used.

While certain specific dyes have been men tioned herein, it is to be understood that these dyes have been set forth merely by way of example.

I have discovered that the methyl ester of alpha hydroxy propionic acid, commonly called methyl lactate, when used' as a solvent ingredient in wood stains produces far reachingimprovements in the finished product.' These results are all the more remarkable in view of the fact that the higher esters of lactic acid, such, for instance, as butyl lactate, have proved unsatisfactory. As illustrations of the present invention, the following examples of wood stain compositions containing methyl lactatemay be noted. The parts are by volume except for the Example 1 Methyl lactate part 1 Methyl alcohol parts 5% Ethyl alcohol do 4 Toluol do 5 Water soluble aniline dye per gallon of stain ounces 1to 4- A reducer solution for wood-stains may be prepared according to the following example:

Example 2 Y I Parts Methyl lactate; 1% Methyl alcohol 5%, Ethyl alcohol 4% Toluol 5 While ethyl alcohol is preferred in the above examples, it may be replaced with methyl alcohol, isopropyl alcohol, or acetone. Toluol is preferred for a number of reasons but equivalents such as xylol, benzol, solvent naphtha, benzene, turpentine or dipentene may be used without deuse of methyl lactate makes it possible to produce a practical wood stain reducer solution wherein the increase in the amount of the solvent ingredient. necessary'is extremely small as compared with substantial!!!- creases heretofore necessary. Methyl lactate has ,the further advantage of making it possible to produce so-called heavy color stains containing as high as 6 ounces of color per gallon of wood stain without an undue increase in the methyl lactate content. In addition to these specific advantages, wood stains made with methyl lactate give better penetration than other nongrain raising wood stains made from water soluble aniline dyes, for the methyl lactate gives stains that are non-hygroscopic.

While methyl lactate has been referred to above as the solvent ingredient for the improved wood stain composition which is the subject of this invention, it is to be understood that the term "solvent ingredient" has been used in the sense of principal solvent ingredient since the methyl lactate may be assisted by such well known solvent assistants as methyl and ethyl alcohol. However, in spite of the fact that the methyl lactate is used in relatively. smaller amounts ,than the assisting ingredients, it is important to note that the methyl lactate, due to its great solvent power, is the principal solvent ingredient in the sense that it is primarily reand such changes should not be deemed to constitute a departure from the spirit of the invention as hereinafter claimed.

Having thus described my invention, I claim:

. A wood stain containing a water-soluble aniline dye in solution in methyl lactate, which constitutes the essential dye-solvent of the stain,

whereby the stain is rendered substantially nonshade-changing prior and penetrant of wood and non-bleeding into to use, non-hygroscopic without raising its grain, lacquer or similar coatings subsequently applied to the stained sur-' face.

2. A wood stain in accordance with claim 1 containing methyl alcohol as a solvent assistant,

and also containing toluol.

' 3. A wood stain in accordance with claim 1 containing methyl and ethyl alcohols as solvent assistants, and also containing toluol.

4. A wood stain in accordance with claim 1 consisting essentially of -1 part methyl lactate, 8 parts methyl alcohol, and 5 parts toluol, together with 1 to 4 ounces of water-soluble aniline dye per gallon of the stain.

5. A wood stain in accordance with claim 1 consisting essentially of 1 part methyl lactate, 5 parts methyl alcohol, 4 parts ethyl alcohol, and 5 parts toluol, together with 1 to 2 ounces of water-soluble aniline dye per gallon of the stain.

6. A reducer for making wood stains of watersoluble aniline dyes as set forth in claim 1, said reducer comprising a minor proportion of methyl lactate as its principal dye-solvent ingredient, together with a. major proportion of solvent assistant.

7. A reducer for making wood stains oi wetersoluble aniline dyes as set forth in claim 1, said reducer consisting essentially of 1% part methyl lactate, aoparts methyl alcohol, and 5 parts toluol.

8. A reducer for making wood stains oiwatersoluble aniline dyes as set forth in claim 1, said reducer consisting essentially of 1% part methyl lactate. 5% parts methyl alcohol, 4% parts ethyl alcohol, and 5 parts toluol.

" nLwoon J. scmssm. 

